Scoliosis can be divided into functional and structural scoliosis. In functional scoliosis, the spinal column has a lateral, usually C-shaped, deviation which is located in the lower breast and lumbar part of the back. This type of scoliosis does not cause pathological changes in the spinal column and therefore barely requires medical treatment.
On the other hand, the structural scolioses are characterised by both a lateral deviation of the spinal column and a twisting thereof. The spinal column shows structural changes by the vertebrae and the intermediate discs being wedge-shaped. The twisting of the spinal column causes, in scoliosis in the breast part of the back, a deformation of the rib cage, which can affect the heart and lung function. This is one of the most difficult complications of the structural scolioses. Among further complications, mention can be made of reduced ability to move.
Structural scoliosis is treated either by means of a corset or by surgery. The extent of the scoliosis is usually determined by measuring the angle between the upper end plate of the upper neutral vertebra and the lower end plate of the lower neutral vertebra. Treatment by means of a corset is normally applied if the scoliosis exceeds 30.degree. and exhibits reliable progress. Scolioses exceeding 40-50.degree. in non-grown-up and 50-60.degree. in grown-up individuals are suitable to treat surgically.
The surgical treatment can be carried out by posterior fusion, anterior fusion or a combination of these techniques.
In posterior fusion, the spinal column is uncovered from the back side, whereupon a brace is usually applied to the concave side of the spinal column. The brace is fixed to the spinal column by means of screws or hooks, and the scoliosis is corrected by the entire structure being clamped together by means of a special instrument. The stability of the corrected spinal column can then be improved by attaching to the convex side a so-called compression brace. The braces are then interconnected by means of transverse braces.
In anterior fusion, the spinal column is uncovered from the trunk side, whereupon the front parts of the spinal column are explored from the convex side thereof. As a rule, four to six discs are uncovered, which are then resected. Holders are fixed to the vertebral bodies by means of screws which are fastened in the spongeous bone of the vertebral body. Then a brace is fixed to the holders in such a manner that the spinal column is corrected, compressed and stabilised. Anterior fusion is above all used in certain types of back deformations in the lower breast and lumbar parts, which cannot be taken care of by posterior fusion. Scolioses with great defects in the rear arcs may be involved, such as myelocele, rigid and grave scolioses, such as congenital scolioses, or grave forms of kyphosis.
Posterior and anterior fusions are preferably combined in the cases where the frequency of pseudoosteoarthrosis is high. Such a combined fusion will also be more stable.
The operation time in a combined fusion may often amount to 10-11 h, which is an inconveniently long time from the viewpoint of both the surgeons and the patient.